Jumbo Frame - Enabling on a VLAN of CAT 6500 running IOS

Jumbo frames needs to be enabled on one of the vlan interface on Cisco 6500 IOS Switch.
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•1) Once enabled the mtu 9216 on the required vlan interface do we need to reload the switch to take effect (I believe that in some low end swicthes it needs a reload)
•2) If we enable only one Vlan interface, how about the other vlan interfaces(about 200 are on this switch)? Do we need to specify mtu1500 on other vlan interfaces?
I have read information at the following two links, but I still wish to reconfirm by asking the questions in this forum. Someone who has already implemented this may have gained more experience while implementing it on CAT 6500 IOS Switch.
https://supportforums.cisco.com/message/963341#963341
http://www.cisco.com/en/US/products/hw/switches/ps700/products_configuration_example09186a008010edab.shtml
http://www.cisco.com/en/US/products/hw/switches/ps700/products_configuration_example09186a008010edab.shtml#backinfo1
Thanks.
Alphonse

You do not need to reboot your 6500 after you enable jumbo frames, but it is good idea to do it during an outage window. You only need to reboot smaller switches i.e. 3560, 3750, etc...after enabling jumbo frames. On these switches you can only enable it globally. Only enable jumbo frames for the vlans you need. You usually need jumbo frames for vlans connecting to the storage systems.
Good Luck

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I have an iMac running 10.6.4 and Airport Utility Version 5.5.1 (551.19). A few weeks ago I enabled Jumbo Frames for some wired gigabit testing. I forgot to change back to 1500 MTU. Tried checking an Airport Setting with the Utility and it discovers the Airport Express (non-gige) but cannot retrieve the configuration. I manage the Airport via ethernet. Changing back to 1500 MTU fixes the issue. Is this expected? The odd thing is that printing works fine to the printer attached to the Airport even at 9000 MTU.

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http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/12_1e/swconfig/redund.htm#wp1095579
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I just got the SG 300-28 28 port switch tonight and got it up and running however, i've encountered a problem regarding jumbo frames. In the documentation and product brochures, it states the SG 300 switches supports jumbo frames up to 10k. When I first setup the switch and enabled jumbo frames, i was getting very slow speeds in my network transfers (800kb/s !!!). All the workstations are running Intel PCIE nic cards with jumbo frames enabled at 9014 bytes. After some troubleshooting, i lowered the frame size to 4088 bytes and everything returned to normal with fast speeds.
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Hi Dickson C,
Interesting query.. TCP, UDP and ICMP packet overhead are fairly negligible according to the information below i would think about 94 bytes for ethernet plus tcp overhead.
The switch would internally label the ethernet frame to identify what VLAN the frame is in (even Vlan 1), so an extra 4 bytes would be used within the switch for that.
Ethernet frame format:
6 byte dest MAC addr
6 byte src MAC addr
[4 byte optional 802.1q VLAN Tag]
2 byte length/type
46-9014 byte data (payload)
4 byte CRC
Ethernet overhead bytes:
12 byte intergap + 8 preamble + 14 header + 4 trailer = 18 bytes/packet w/o 802.1q
12 byte intergap + 8 preamble + 18 header + 4 trailer = 22 bytes/packet with 802.1q
TCP encapsulated in Ethernet:
Assuming no header compression (e.g. not PPP)
Add 20 IPv4 header or 40 IPv6 header (no options)
Add 20 TCP header
Add 12 bytes optional TCP timestamps
TCP overhead can be 52 bytes
Ethernet + TCP overhead around 52+22 bytes = 74 bytes
Your Intel ethernet NIC supports around 9500-byte, so the datasheets from intel suggest for a jumbo frame , but you have it enabled at 9014 bytes.
So your NIC enabled at 9014 bytes - 74 bytes for Ethernet and TCP packet overhead= approximately 8940 bytes of data.
You say you are getting packet data throughput around 8972 bytes.
Check my maths, I have made a few assumptions. What you reckon, worth a call to the Small Business Support center to double check, please open a case and report back with the results. I really may be way off in some of my assumptions.
regards Dave
http://www.cisco.com/en/US/support/tsd_cisco_small_business_support_center_contacts.html

Jumbo Frame support

Hi all
I have a vendor that wants to run an application called mirrorview to do a bandwidth test for a new application; the only requirement is that I support jumbo frames on my uplinks. I do not currently have my ports configured to support jumbo frames, are there any benefits or drawbacks to supporting jumbo frames? If so please post so I can weigh those options before I reconfigure my uplinks.
TIA Rodney.
FYI I am running 6500 hybrid in the core , and 3550-xx at the edge.

If jumbo frames are enabled only on uplinks but not all the way between two systems, then the end systems won't take any advantage of jumbo frames. There is no drawbacks of jumbo frames as such as far as I know, but some pitfalls.
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Another pitfall is that if you enable jumbo frame on any IP-layer interface this will automatically change IP MTU. If you're running OSPF and jumbo frames are enabled only on some systems connected to a subnet but not on other systems from the same subnet OSPF adjacencies will not form until you specify 'ip mtu 1500' on jumbo-enabled systems. As soon as you do this, effect of jumbo frames for IP traffic will be void (but it might still be necessary for things like MPLS). So be sure that systems on common subnet have same MTU.
Routing problem is easy to detect, more general problem is that travelling across L2-only path there is no way for switches to send 'ICMP Fragmentation required' if packet is large then next interface MTU. This will break PMTU Discovery and since most applications usually sent packets at max MTU and DF-bit set, there will be timeouts. So again, consistent MTU across whole L2 path is important.
By the way, if your servers and PC's are not connected via jumbo-enabled links then you unlikely see any difference by enabling jumbo frames on the uplinks because both 6500 and 3550 catalysts are capable of wirespeed performance. The only time when it makes sense to enable jumbo frames only on the core links is when you need some non-IP headers to encapsulate your max-sized IP packets (MPLS is one such example).
As for benefits - servers running (very) heavy traffic applications (think full-feed USENET server with multiple fast peerings) may benefit from sending large portion of data in each packet, so for the same amount of data they need less number of packets. Destination system will have to handle less interrupts and overall performance may increase.
Hope this helps.

Airport Utility on iMac with Jumbo Frames can't read Airport configuration

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Message was edited by: Gaijin Kuma

None of Apple's Airports support jumbo frames.
The networking chip that Apple uses in the Airport Extreme has the capability to support jumbo frames, but it isn't an option that Apple has chosen to expose to the user. So you can't reliably use the Airports on a jumbo frame enabled subnet.
The likely reason the Internet is still working is that, unless your uploading, it's unlikely the iMac sent a packet in excess of 1500 bytes to the Airport. The Airport is always sending 1500 byte packets which your iMac wold receive fine regardless of what the MTU was set (well, unless it was set below 1500).
Some people do report success but I would be wary of their results, they may not have down/upped the interface so the MTU may have been listed as changed, but not yet actually changed to the larger MTU. No-one has actually posted a tcpdump -e capture showing an Airport actually sending/receiving packets in excess of 1500 bytes.
Some more links to this discussion topic-
http://discussions.apple.com/thread.jspa?threadID=1085469
http://discussions.apple.com/thread.jspa?threadID=1222397
http://www.smallnetbuilder.com/content/view/30188/96/

SRW2048 and Jumbo frames

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Any help or suggestions would be appreciated.
Thanks.
David

On the SF-300 and SG-300 for Jumbo to work the Enable Jumbo checkbox must be unchecked. Either I don't understand Cisco logic or it's a bug in the GUI.

Aggregates, VLAN's, Jumbo-Frames and cluster interconnect opinions

Hi All,
I'm reviewing my options for a new cluster configuration and would like the opinions of people with more expertise than myself out there.
What I have in mind as follows:
2 x X4170 servers with 8 x NIC's in each.
On each 4170 I was going to configure 2 aggregates with 3 nics in each aggregate as follows
igb0 device in aggr1
igb1 device in aggr1
igb2 device in aggr1
igb3 stand-alone device for iSCSI network
e1000g0 device in aggr2
e1000g1 device in aggr2
e1000g2 device in aggr3
e1000g3 stand-alone device of iSCSI network
Now, on top of these aggregates, I was planning on creating VLAN interfaces which will allow me to connect to our two "public" network segments and for the cluster heartbeat network.
I was then going to configure the vlan's in an IPMP group for failover. I know there are some questions around that configuration in the sense that IPMP will not detect a nic failure if a NIC goes offline in the aggregate, but I could monitor that in a different manner.
At this point, my questions are:
[1] Are vlan's, on top of aggregates, supported withing Solaris Cluster? I've not seen anything in the documentation to mention that it is, or is not for that matter. I see that vlan's are supported, inluding support for cluster interconnects over vlan's.
Now with the standalone interface I want to enable jumbo frames, but I've noticed that the igb.conf file has a global setting for all nic ports, whereas I can enable it for a single nic port in the e1000g.conf kernel driver. My questions are as follows:
[2] What is the general feeling with mixing mtu sizes on the same lan/vlan? Ive seen some comments that this is not a good idea, and some say that it doesnt cause a problem.
[3] If the underlying nic, igb0-2 (aggr1) for example, has 9k mtu enabled, I can force the mtu size (1500) for "normal" networks on the vlan interfaces pointing to my "public" network and cluster interconnect vlan. Does anyone have experience of this causing any issues?
Thanks in advance for all comments/suggestions.

For 1) the question is really "Do I need to enable Jumbo Frames if I don't want to use them (neither public nore private network)" - the answer is no.
For 2) each cluster needs to have its own seperate set of VLANs.
Greets
Thorsten

Enable Jumbo Frame Support On UCS

Could someone direct me to the documentation for the proper way to enable jumbo frame support on UCS? I'm trying to troubleshoot a problem and have configured MTU of 9000 from ESX running on a blade to an NFS server off a Nexus 5k. I have good documentation for configuring jumbo frame support on the Nexus 5k and on ESX but nothing really specific for UCS.
For Nexus 5k:
http://www.cisco.com/en/US/docs/switches/datacenter/nexus5000/sw/configuration/nxos/Cisco_Nexus_5000_Series_NX-OS_Software_Configuration_Guide_chapter33.html#con_1150612
show run:
policy-map type network-qos jumbo
class type network-qos class-default
mtu 9216
system qos
service-policy type network-qos jumbo
For ESXi:
esxcfg-vswitch -m 9000 vSwitch0
esxcfg-vswitch -A IP_Storage vSwitch0
esxcfg-vswitch -v 31 -p IP_Storage vSwitch0
esxcfg-vmknic -a -i 10.254.31.2 -n 255.255.255.192 -m 9000 "IP_Storage"
Testing:
I have been able to ping (with large payload) the NFS host interface from a temporary vlan interface on the N5k. I cannot do the same to the ESX hosts or between hosts.
Thanks,
-R

Russell
What network adapter are you using? M81KR or the M71KR's or any other?
The MTU is set on a per CoS basis in UCS. If you do not have any QoS policy defined for the vNIC that is going to the vSwitch, then the traffic is going to Best-Effort Class. All you need to do to enable jumbo frames is to enter the MTU to be 9000 in the MTU pulldown for whatever class the traffic is going to.
Its also given in the user guide -
http://www.cisco.com/en/US/docs/unified_computing/ucs/sw/gui/config/guide/1.3.1/UCSM_GUI_Configuration_Guide_1_3_1_chapter18.html
MTU drop-down list
The maximum transmission unit for the channel. This can be:
An integer between 1500 and 9216. This value corresponds to the maximum packet size.
fc—A predefined packet size of 2240.
normal—A predefined packet size of 1500.
Note
This field is always set to fc for Fibre Channel.
--Manish

Enabling Jumbo Frames in Solaris 10 with Intel NIC

Hello all! I have a Solaris 10 machine with dual Intel NICs that I wish to enable jumbo frames on, but I am unable to find any clear guidance on how to do so. Could someone either provide guidance on this or point me in the proper direction?
Thank you in advance!

Hello all! I have a Solaris 10 machine with dual Intel NICs that I wish to enable jumbo frames on, but I am unable to find any clear guidance on how to do so. Could someone either provide guidance on this or point me in the proper direction?
Thank you in advance!

Enabling Jumbo Frames in CISCO Switch

Hi,
I have tried to enable jumbo frames by:
Go to Port Management >> Port Settings
Enable Jumbo Frames. Click Apply.
Save configuration and reboot
After that I try to verify that jumbo frames is really working by looking at the Status and Statistics >> RMON >> Statistics.
It seems that the page only shows frame size of up to 1632 Bytes. Does this mean that the Jumbo Frames are not working? Is this the correct way to verify that Jumbo frames are enabled?
Thanks.
James

Hi,
This setting allows the frames to pass on the switch, nothing more. The rest of the devices needs to capable to send and receive such frames as well. You need to configure the NICs and possibly applications to do this.
Make sure all communicating devices are capable of jumbo frames. If you mix them you will have trouble.
For a sample how to do this on linux see
https://wiki.archlinux.org/index.php/Jumbo_Frames
Hope this helps.

SRW2008 - How To Enable Jumbos Frames?

Title says it all....
How do you enable jumbo frames on an SRW2008?
The data sheet says it supports jumbo frames, but the manual does not say how to enable, and I did not find it in the Web GUI.
It just occured to me (light dawns on marblehead) - perhaps this needs to be done via the CLI?
TIA.

Title says it all....
How do you enable jumbo frames on an SRW2008?
The data sheet says it supports jumbo frames, but the manual does not say how to enable, and I did not find it in the Web GUI.
It just occured to me (light dawns on marblehead) - perhaps this needs to be done via the CLI?
TIA.
Hi,
Check out the below link
http://portforward.com/routergui/Linksys/SRW2008/Jumbo_Frame.htm
Hope to Help !!
Ganesh.H
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Adjust MTU on my Time Capsule to enable Jumbo Frames?

Is there a way to adjust the MTU setting on my Time Capsule to enable Jumbo Frames? I have the most current Airport Utilities and firmware on my TC.

There is no way to adjust MTU on either WAN or LAN ports on the TC. At least AFAIK.. Apple do not allow users to access that depth of control.
Get a gigabit switch and plug everything into that if you want jumbo frames for local network.. Jumbo frames will obviously cause slow down on the router to the internet and I guess is why Apple doesn't use them.

Jumbo Frame - Enabling on a VLAN of CAT 6500 running IOS

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